On Wed, Aug 12, 2015 at 01:03:36PM -0600, Jeff Law wrote: > On 08/12/2015 12:57 PM, Richard Sandiford wrote: > >Jeff Law <l...@redhat.com> writes: > >>On 08/10/2015 06:05 AM, tbsaunde+...@tbsaunde.org wrote: > >>>From: Trevor Saunders <tbsaunde+...@tbsaunde.org> > >>> > >>>Hi, > >>> > >>>In many places gcc puts classes in the anon namespace so the compiler can > >>>tell > >>>they do not get inheritted from to enable better devirtualization. However > >>>debugging code in the anon namespace can be a pain, and the same thing can > >>>be > >>>accomplished more directly by marking the classes as final. When > >>>bootstrapping > >>>stage 3 should always be built in C++14 mode now, and of course will > >>>always be > >>>newer than gcc 4.7, so these classes will always be marked as final there. > >>>AIUI cross compilers are supposed to be built with recent gcc, which I > >>>would > >>>tend to think implies newer than 4.7, so they should also be built with > >>>these > >>>classes marked as final. I believe that means in all important cases > >>>this works just as well as the anon namespace. > >>> > >>>bootstrapped + regtested on x86_64-linux-gnu, ok? > >>> > >>>Trev > >>> > >>> > >>>gcc/ChangeLog: > >>> > >>>2015-08-10 Trevor Saunders <tbsau...@tbsaunde.org> > >>> > >>> * compare-elim.c, dce.c, dse.c, gimple-ssa-isolate-paths.c, > >>> gimple-ssa-strength-reduction.c, graphite.c, init-regs.c, > >>> ipa-pure-const.c, ipa-visibility.c, ipa.c, mode-switching.c, > >>> omp-low.c, reorg.c, sanopt.c, trans-mem.c, tree-eh.c, > >>> tree-if-conv.c, tree-ssa-copyrename.c, tree-ssa-dce.c, > >>> tree-ssa-dom.c, tree-ssa-dse.c, tree-ssa-forwprop.c, > >>> tree-ssa-sink.c, tree-ssanames.c, tree-stdarg.c, tree-tailcall.c, > >>> tree-vect-generic.c, tree.c, ubsan.c, var-tracking.c, > >>> vtable-verify.c, web.c: Use GCC_FINAL instead of the anonymous > >>>namespace. > >>OK. > > > >I was hoping someone else was going to speak up since I seem > >to have been posting a few negative messages recently, but I think > >this is really a step in the wrong direction. I think the code > >was using anonymous namespaces in exactly the way they were
are they actually all that common? I think gcc is the only C++ with which I'm familiar that uses them much. > >intended to be used. > No need to worry about seeming to be negative. > > > The problem is you can't get to stuff in the anonymous namespace easily in > the debugger. There was talk of fixing that, but I don't think it ever went > forward on the gdb side. > > If gdb were to get fixed so that debugging this stuff was easier, then I'd > fully support putting things back into the anonymous namespace. I have vague memories of other reasons to dislike the anon namespace being brought up when it was discussed at $day job, but debuggers was the big reason (and its not just gdb that's bad) Trev > > jeff >
